Recurrent Germline DLST Mutations in Individuals with Multiple Pheochromocytomas and Paragangliomas.

Pheochromocytomas and paragangliomas (PPGLs) provide some of the clearest genetic evidence for the critical role of metabolism in the tumorigenesis process. Approximately 40% of PPGLs are caused by driver germline mutations in 16 known susceptibility genes, and approximately half of these genes encode members of the tricarboxylic acid (TCA) cycle. Taking as a starting point the involvement of the TCA cycle in PPGL development, we aimed to identify unreported mutations that occurred in genes involved in this key metabolic pathway and that could explain the phenotypes of additional individuals who lack mutations in known susceptibility genes. To accomplish this, we applied a targeted sequencing of 37 TCA-cycle-related genes to DNA from 104 PPGL-affected individuals with no mutations in the major known predisposing genes. We also performed omics-based analyses, TCA-related metabolite determination, and 13C5-glutamate labeling assays. We identified five germline variants affecting DLST in eight unrelated individuals (∼7%); all except one were diagnosed with multiple PPGLs. A recurrent variant, c.1121G>A (p.Gly374Glu), found in four of the eight individuals triggered accumulation of 2-hydroxyglutarate, both in tumors and in a heterologous cell-based assay designed to functionally evaluate DLST variants. p.Gly374Glu-DLST tumors exhibited loss of heterozygosity, and their methylation and expression profiles are similar to those of EPAS1-mutated PPGLs; this similarity suggests a link between DLST disruption and pseudohypoxia. Moreover, we found positive DLST immunostaining exclusively in tumors carrying TCA-cycle or EPAS1 mutations. In summary, this study reveals DLST as a PPGL-susceptibility gene and further strengthens the relevance of the TCA cycle in PPGL development.

Changes in intolerance of uncertainty over the course of treatment predict posttraumatic stress disorder symptoms in an inpatient sample.

Intolerance of uncertainty (IU) is the inability to tolerate distress that arises in response to the absence of important information. The level of IU has been investigated across various psychological disorders; however, few studies have examined IU in trauma-affected samples. We aimed to investigate the relationship between IU and posttraumatic stress disorder (PTSD) across the course of treatment. Participants (n = 106) had a diagnosis of PTSD and were from first responder, military, and occupational injury backgrounds. Participants completed self-report questionnaires pre- and post-engagement in an inpatient group trauma-informed psychoeducation and skills (TIPS) intervention. Regression analyses indicated that decreases in overall and inhibitory IU were associated with decreases in PTSD severity overall and at the symptom cluster level. However, prospective IU was only associated with changes in the re-experiencing, avoidance, and arousal PTSD symptom clusters. Our findings are congruent with the nascent literature indicating that IU may be a maintaining factor for PTSD, suggesting clinical relevance for attendance to IU within the course of treatment.

Preclinical toxicology profile of squalene epoxidase inhibitors.

Small cell lung cancer (SCLC) is a particularly aggressive subset of lung cancer, and identification of new therapeutic options is of significant interest. We recently reported that SCLC cell lines display a specific vulnerability to inhibition of squalene epoxidase (SQLE), an enzyme in the cholesterol biosynthetic pathway that catalyzes the conversion of squalene to 2,3-oxidosqualene. Since it has been reported that SQLE inhibition can result in dermatitis in dogs, we conducted a series of experiments to determine if SQLE inhibitors would be tolerated at exposures predicted to drive maximal efficacy in SCLC tumors. Detailed profiling of the SQLE inhibitor NB-598 showed that dogs did not tolerate predicted efficacious exposures, with dose-limiting toxicity due to gastrointestinal clinical observations, although skin toxicities were also observed. To extend these studies, two SQLE inhibitors, NB-598 and Cmpd-4″, and their structurally inactive analogs, NB-598.ia and Cmpd-4″.ia, were profiled in monkeys. While both active SQLE inhibitors resulted in dose-limiting gastrointestinal toxicity, the structurally similar inactive analogs did not. Collectively, our data demonstrate that significant toxicities arise at exposures well below the predicted levels needed for anti-tumor activity. The on-target nature of the toxicities identified is likely to limit the potential therapeutic utility of SQLE inhibition for the treatment of SCLC.

Aldosterone inactivates the endothelin-B receptor via a cysteinyl thiol redox switch to decrease pulmonary endothelial nitric oxide levels and modulate pulmonary arterial hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) is characterized, in part, by decreased endothelial nitric oxide (NO(·)) production and elevated levels of endothelin-1. Endothelin-1 is known to stimulate endothelial nitric oxide synthase (eNOS) via the endothelin-B receptor (ET(B)), suggesting that this signaling pathway is perturbed in PAH. Endothelin-1 also stimulates adrenal aldosterone synthesis; in systemic blood vessels, hyperaldosteronism induces vascular dysfunction by increasing endothelial reactive oxygen species generation and decreasing NO(·) levels. We hypothesized that aldosterone modulates PAH by disrupting ET(B)-eNOS signaling through a mechanism involving increased pulmonary endothelial oxidant stress. METHODS AND RESULTS: In rats with PAH, elevated endothelin-1 levels were associated with elevated aldosterone levels in plasma and lung tissue and decreased lung NO(·) metabolites in the absence of left-sided heart failure. In human pulmonary artery endothelial cells, endothelin-1 increased aldosterone levels via peroxisome proliferator-activated receptor gamma coactivator-1α/steroidogenesis factor-1-dependent upregulation of aldosterone synthase. Aldosterone also increased reactive oxygen species production, which oxidatively modified cysteinyl thiols in the eNOS-activating region of ET(B) to decrease endothelin-1-stimulated eNOS activity. Substitution of ET(B)-Cys405 with alanine improved ET(B)-dependent NO(·) synthesis under conditions of oxidant stress, confirming that Cys405 is a redox-sensitive thiol that is necessary for ET(B)-eNOS signaling. In human pulmonary artery endothelial cells, mineralocorticoid receptor antagonism with spironolactone decreased aldosterone-mediated reactive oxygen species generation and restored ET(B)-dependent NO(·) production. Spironolactone or eplerenone prevented or reversed pulmonary vascular remodeling and improved cardiopulmonary hemodynamics in 2 animal models of PAH in vivo. CONCLUSIONS: Our findings demonstrate that aldosterone modulates an ET(B) cysteinyl thiol redox switch to decrease pulmonary endothelium-derived NO(·) and promote PAH.

Glutathione peroxidase-3 deficiency promotes platelet-dependent thrombosis in vivo.

BACKGROUND: Glutathione peroxidase-3 (GPx-3) is a selenocysteine-containing plasma protein that scavenges reactive oxygen species in the extracellular compartment. A deficiency of this enzyme has been associated with platelet-dependent thrombosis, and a promoter haplotype with reduced function has been associated with stroke risk. METHODS AND RESULTS: We recently developed a genetic mouse model to assess platelet function and thrombosis in the setting of GPx-3 deficiency. The GPx-3((-/-)) mice showed an attenuated bleeding time and an enhanced aggregation response to the agonist ADP compared with wild-type mice. GPx-3((-/-)) mice displayed increased plasma levels of soluble P-selectin and decreased plasma cyclic cGMP compared with wild-type mice. ADP infusion-induced platelet aggregation in the pulmonary vasculature produced a more robust platelet activation response in the GPx-3((-/-)) than wild-type mice; histological sections from the pulmonary vasculature of GPx-3((-/-)) compared with wild-type mice showed increased platelet-rich thrombi and a higher percentage of occluded vessels. Cremaster muscle preparations revealed endothelial dysfunction in the GPx-3((-/-)) compared with wild-type mice. With a no-flow ischemia-reperfusion stroke model, GPx-3((-/-)) mice had significantly larger cerebral infarctions compared with wild-type mice and platelet-dependent strokes. To assess the neuroprotective role of antioxidants in this model, we found that manganese(III) meso-tetrakis(4-benzoic acid)porphyrin treatment reduced stroke size in GPx-3((-/-)) mice compared with vehicle-treated controls. CONCLUSIONS: These findings demonstrate that GPx-3 deficiency results in a prothrombotic state and vascular dysfunction that promotes platelet-dependent arterial thrombosis. These data illustrate the importance of this plasma antioxidant enzyme in regulating platelet activity, endothelial function, platelet-dependent thrombosis, and vascular thrombotic propensity.

Pharmacokinetic, biodistribution, and biophysical profiles of TNF nanobodies conjugated to linear or branched poly(ethylene glycol).

Covalent attachment of poly(ethylene glycol) (PEG) to therapeutic proteins has been used to prolong in vivo exposure of therapeutic proteins. We have examined pharmacokinetic, biodistribution, and biophysical profiles of three different tumor necrosis factor alpha (TNF) Nanobody-40 kDa PEG conjugates: linear 1 × 40 KDa, branched 2 × 20 kDa, and 4 × 10 kDa conjugates. In accord with earlier reports, the superior PK profile was observed for the branched versus linear PEG conjugates, while all three conjugates had similar potency in a cell-based assay. Our results also indicate that (i) a superior PK profile of branched versus linear PEGs is likely to hold across species, (ii) for a given PEG size, the extent of PEG branching affects the PK profile, and (iii) tissue penetration may differ between linear and branched PEG conjugates in a tissue-specific manner. Biophysical analysis (R(g)/R(h) ratio) demonstrated that among the three protein-PEG conjugates the linear PEG conjugate had the most extended time-average conformation and the most exposed surface charges. We hypothesized that these biophysical characteristics of the linear PEG conjugate accounts for relatively less optimal masking of sites involved in elimination of the PEGylated Nanobodies (e.g., intracellular uptake and proteolysis), leading to lower in vivo exposure compared to the branched PEG conjugates. However, additional studies are needed to test this hypothesis.

65% Parahydrogen from a liquid nitrogen cooled generator.

The isomeric enrichment of parahydrogen (pH2) gas is readily accomplished by lowering the gas temperature in the presence of a catalyst. This enrichment is often pursued at two distinct temperatures: ∼51% pH2 is generated at liquid nitrogen temperatures (77 K), while nearly 100% pH2 can be produced at 20 K. While the liquid nitrogen cooled generator is attractive due to the low cost of entry, there are benefits to having access to greater than 51% pH2 for enhanced NMR applications. In this work, we introduce a low-cost modification to an existing laboratory-constructed liquid nitrogen cooled pH2 generator that provides âˆ¼ 65% pH2. This modification takes advantage of vacuum-mediated boiling point suppression of liquid nitrogen, allowing the temperature of the liquid to be lowered from 77 K to nitrogen's triple point of 63 K. The reduced temperature allowed for the generation of parahydrogen fractions of 63-67% at gas flow rates from 20 to 1000 standard cubic centimeters per minute. We compare this to equivalent experiments that did not utilize the temperature-lowering effects of pressure reduction; these controls generally maintained pH2 fractions of âˆ¼ 50%. All results (experimental and control) agree with the theoretically expected parahydrogen generation at these temperatures. This straightforward modification to an existing pH2 generator may be of interest to a broad range of scientists involved with parahydrogen research by introducing a simple and low-cost entryway to increased pH2 fractions using a conventional liquid nitrogen cooled generator.

Glutathione peroxidase-1 modulates lipopolysaccharide-induced adhesion molecule expression in endothelial cells by altering CD14 expression.

CD14 contributes to LPS signaling in leukocytes through formation of toll-like receptor 4/CD14 receptor complexes; however, a specific role for endogenous cell-surface CD14 in endothelial cells is unclear. We have found that suppression of glutathione peroxidase-1 (GPx-1) in human microvascular endothelial cells increases CD14 gene expression compared to untreated or siControl (siCtrl)-treated conditions. Following LPS treatment, GPx-1 deficiency augmented LPS-induced intracellular reactive oxygen species accumulation, CD14 expression, and intercellular adhesion molecule-1 (ICAM-1) mRNA and protein expression compared to LPS-treated control cells. GPx-1 deficiency also transiently augmented LPS-induced vascular cell adhesion molecule-1 (VCAM-1) expression. Adenoviral overexpression of GPx-1 significantly diminished LPS-mediated responses in adhesion molecule expression. Consistent with these findings, LPS responses were also greater in endothelial cells derived from GPx-1-knockout mice, whereas adhesion molecule expression was decreased in cells from GPx-1-overexpressing transgenic mice. Knockdown of CD14 attenuated LPS-mediated up-regulation of ICAM-1 and VCAM-1 mRNA and protein, and it mitigated the effects of GPx-1 deficiency on LPS-induced adhesion molecule expression. Taken together, these data suggest that GPx-1 modulates the endothelial cell response to LPS, in part, by altering CD14-mediated effects.

Clinical utilization of deployed military surgeons.

BACKGROUND: Combat casualty care has been shaped by the prolonged conflicts in Southwest Asia, namely Afghanistan, Iraq, and Syria. The utilization of surgeons in austere locations outside of Southwest Asia and its implication on skill retention and value have not been examined. This study hypothesizes that surgeon utilization is low in the African theater. This lack of activity is potentially damaging to surgical skill retention and patient care. METHODS: Military case logs of surgeons deployed to Africa under command of Special Operations Command Africa between January 1, 2016, and January 1, 2020, were examined. Cases were organized based on population served, general type of procedure, current procedural terminology codes, and location. RESULTS: Twenty deployment caseloads representing 74% of the deployments during the period were analyzed. In 3,294 days, 101 operations were performed, which included 45 on combat/terrorism related injuries and 19 on US personnel. East and West African deployments, combat, and noncombat zones, respectively, were compared. East Africa averaged 4.1 ± 3.8 operations per deployment, and West Africa, 7.3 ± 8.0 (p = 0.2434). In East Africa, 56.1% of total operations were related to combat/terrorism, compared with 29.6% of total operations in West Africa (p = 0.0077). West Africa had a significantly higher proportion of elective (p = 0.0002) and humanitarian cases (p = <0.0001). CONCLUSION: Surgical cases for military surgeons were uncommon in Africa. The low volumes have implications for skill retention, morale, and sustainability of military surgical end strength. Reduction in deployment lengths, deployment location adjustments, and/or skill retention strategies are required to ensure clinical peak performance and operational readiness. Failure to implement changes to current practices to optimize surgeon experience will likely decrease surgical readiness and could contribute to decreased retention of deployable military surgeons to support global operations. LEVEL OF EVIDENCE: Economic/decision, level III.

Sustained Delivery of SB-431542, a Type I Transforming Growth Factor Beta-1 Receptor Inhibitor, to Prevent Arthrofibrosis.

Fibrosis of the knee is a common disorder resulting from an aberrant wound healing response and is characterized by extracellular matrix deposition, joint contraction, and scar tissue formation. The principal regulator of the fibrotic cascade is transforming growth factor beta-1 (TGF-ß1), a factor that induces rapid proliferation and differentiation of resident fibroblasts. In this study, we demonstrate successful inhibition of TGF-ß1-driven myofibroblastic differentiation in human fibroblast-like synoviocytes using a small molecule TGF-ß1 receptor inhibitor, SB-431542. We also demonstrate successful encapsulation of SB-431542 in poly(D,L-lactide-co-glycolide) (PLGA) as a potential prophylactic treatment for arthrofibrosis and characterize drug release and bioactivity in a three-dimensional collagen gel contraction assay. We assessed the effects of TGF-ß1 and SB-431542 on cell proliferation and viability in monolayer cultures. Opposing dose-dependent trends were observed in cell proliferation, which increased in TGF-ß1-treated cultures and decreased in SB-431542-treated cultures relative to control (p < 0.05). SB-431542 was not cytotoxic at the concentrations studied (0-50 µM) and inhibited TGF-ß1-induced collagen gel contraction in a dose-dependent manner. Specifically, TGF-ß1-treated gels contracted to 18% ± 1% of their initial surface area, while gels treated with TGF-ß1 and ≥10 µM SB-431542 showed no evidence of contraction (p < 0.0001). Upon removal of the compound, all gels contracted to control levels after 44 h in culture, necessitating sustained delivery for prolonged inhibition. To this end, SB-431542 was encapsulated in PLGA microspheres (SBMS) that had an average diameter of 87.5 ± 24 µm and a loading capacity of 4.3 µg SB-431542 per milligram of SBMS. Functional assessment of SBMS revealed sustained inhibition of TGF-ß1-induced gel contraction as well as hallmark features of myofibroblastic differentiation, including α-smooth muscle actin expression and connective tissue growth factor production. These results suggest that SB-431542 may be used to counter TGF-ß1-driven events in the fibrotic cascade in the knee cartilage. Impact statement Arthrofibrosis is the most prevalent comorbidity resulting from orthopedic procedures such as total knee arthroplasty that is characterized by excess deposition and accumulation of extracellular matrix. Despite its prevalence, treatments are generally palliative, and there is no effective prophylactic therapy. We report that the small molecule transforming growth factor beta-1 (TGF-ß1) receptor inhibitor, SB-431542, can inhibit the TGF-ß1-driven myofibroblastic differentiation of fibroblast-like synoviocytes. To provide sustained inhibition, we explored the use of SB-laden microspheres as a prophylactic therapy in a three-dimensional contraction model of fibrosis and propose that such therapies will have the potential to improve the standard of care for arthrofibrosis.

Long-gap peripheral nerve repair through sustained release of a neurotrophic factor in nonhuman primates.

Severe injuries to peripheral nerves are challenging to repair. Standard-of-care treatment for nerve gaps >2 to 3 centimeters is autografting; however, autografting can result in neuroma formation, loss of sensory function at the donor site, and increased operative time. To address the need for a synthetic nerve conduit to treat large nerve gaps, we investigated a biodegradable poly(caprolactone) (PCL) conduit with embedded double-walled polymeric microspheres encapsulating glial cell line-derived neurotrophic factor (GDNF) capable of providing a sustained release of GDNF for >50 days in a 5-centimeter nerve defect in a rhesus macaque model. The GDNF-eluting conduit (PCL/GDNF) was compared to a median nerve autograft and a PCL conduit containing empty microspheres (PCL/Empty). Functional testing demonstrated similar functional recovery between the PCL/GDNF-treated group (75.64 ± 10.28%) and the autograft-treated group (77.49 ± 19.28%); both groups were statistically improved compared to PCL/Empty-treated group (44.95 ± 26.94%). Nerve conduction velocity 1 year after surgery was increased in the PCL/GDNF-treated macaques (31.41 ± 15.34 meters/second) compared to autograft (25.45 ± 3.96 meters/second) and PCL/Empty (12.60 ± 3.89 meters/second) treatment. Histological analyses included assessment of Schwann cell presence, myelination of axons, nerve fiber density, and g-ratio. PCL/GDNF group exhibited a statistically greater average area occupied by individual Schwann cells at the distal nerve (11.60 ± 33.01 µm2) compared to autograft (4.62 ± 3.99 µm2) and PCL/Empty (4.52 ± 5.16 µm2) treatment groups. This study demonstrates the efficacious bridging of a long peripheral nerve gap in a nonhuman primate model using an acellular, biodegradable nerve conduit.

Structure and inhibition mechanism of the catalytic domain of human squalene epoxidase.

Squalene epoxidase (SQLE), also known as squalene monooxygenase, catalyzes the stereospecific conversion of squalene to 2,3(S)-oxidosqualene, a key step in cholesterol biosynthesis. SQLE inhibition is targeted for the treatment of hypercholesteremia, cancer, and fungal infections. However, lack of structure-function understanding has hindered further progression of its inhibitors. We have determined the first three-dimensional high-resolution crystal structures of human SQLE catalytic domain with small molecule inhibitors (2.3 Å and 2.5 Å). Comparison with its unliganded state (3.0 Å) reveals conformational rearrangements upon inhibitor binding, thus allowing deeper interpretation of known structure-activity relationships. We use the human SQLE structure to further understand the specificity of terbinafine, an approved agent targeting fungal SQLE, and to provide the structural insights into terbinafine-resistant mutants encountered in the clinic. Collectively, these findings elucidate the structural basis for the specificity of the epoxidation reaction catalyzed by SQLE and enable further rational development of next-generation inhibitors.

A chemical biology screen identifies a vulnerability of neuroendocrine cancer cells to SQLE inhibition.

Aberrant metabolism of cancer cells is well appreciated, but the identification of cancer subsets with specific metabolic vulnerabilities remains challenging. We conducted a chemical biology screen and identified a subset of neuroendocrine tumors displaying a striking pattern of sensitivity to inhibition of the cholesterol biosynthetic pathway enzyme squalene epoxidase (SQLE). Using a variety of orthogonal approaches, we demonstrate that sensitivity to SQLE inhibition results not from cholesterol biosynthesis pathway inhibition, but rather surprisingly from the specific and toxic accumulation of the SQLE substrate, squalene. These findings highlight SQLE as a potential therapeutic target in a subset of neuroendocrine tumors, particularly small cell lung cancers.

The United States Department of Energy's Regional Carbon Sequestration Partnerships Program Validation Phase.

This paper reviews the Validation Phase (Phase II) of the Department of Energy's Regional Carbon Sequestration Partnerships initiative. In 2003, the U.S. Department of Energy created a nationwide network of seven Regional Carbon Sequestration Partnerships (RCSP) to help determine and implement the technology, infrastructure, and regulations most appropriate to promote carbon sequestration in different regions of the nation. The objectives of the Characterization Phase (Phase I) were to characterize the geologic and terrestrial opportunities for carbon sequestration; to identify CO(2) point sources within the territories of the individual partnerships; to assess the transportation infrastructure needed for future deployment; to evaluate CO(2) capture technologies for existing and future power plants; and to identify the most promising sequestration opportunities that would need to be validated through a series of field projects. The Characterization Phase was highly successful, with the following achievements: established a national network of companies and professionals working to support sequestration deployment; created regional and national carbon sequestration atlases for the United States and portions of Canada; evaluated available and developing technologies for the capture of CO(2) from point sources; developed an improved understanding of the permitting requirements that future sequestration activities will need to address as well as defined the gap in permitting requirements for large scale deployment of these technologies; created a raised awareness of, and support for, carbon sequestration as a greenhouse gas (GHG) mitigation option, both within industry and among the general public; identified the most promising carbon sequestration opportunities for future field tests; and established protocols for project implementation, accounting, and management. Economic evaluation was started and is continuing and will be a factor in project selection. During the Validation Phase, the seven regional partnerships will put the knowledge learned during the Characterization Phase into practice through field tests that will validate carbon sequestration technologies that are best suited to their respective regions of the country. These tests will verify technologies developed through DOE's core R&D effort and enable implementation of CO(2) sequestration on a large scale, should that become necessary. Pilot projects will have a site-specific focus to test technology; assess formation storage capacity and injectivity; validate and refine existing CO(2) formation models used to determine the transport and fate of CO(2) in the formation; demonstrate the integrity of geologic seals to contain CO(2); validate monitoring, mitigation, and verification (MMV) technologies; define project costs and compare costs of alternatives; assess potential operational and long-term storage risks; address regulatory requirements; and engage and evaluate public acceptance of sequestration technologies. Field validation tests involving both sequestration in geologic formations and terrestrial sequestration are being developed. The results from the Validation Phase will help to confirm the estimates made during the Characterization Phase and will be used to update the regional atlases and NatCarb. Answers to many questions about the effectiveness and safety of carbon sequestration technologies will be instrumental in planning for a Deployment Phase, in which large volume tests will be planned to further sequestration as an option that can mitigate GHG emissions in the United States.

Current Therapeutic Strategies for Adipose Tissue Defects/Repair Using Engineered Biomaterials and Biomolecule Formulations.

Tissue engineered scaffolds for adipose restoration/repair has significantly evolved in recent years. Patients requiring soft tissue reconstruction, caused by defects or pathology, require biomaterials that will restore void volume with new functional tissue. The gold standard of autologous fat grafting (AFG) is not a reliable option. This review focuses on the latest therapeutic strategies for the treatment of adipose tissue defects using biomolecule formulations and delivery, and specifically engineered biomaterials. Additionally, the clinical need for reliable off-the-shelf therapies, animal models, and challenges facing current technologies are discussed.

Controlled dexamethasone delivery via double-walled microspheres to enhance long-term adipose tissue retention.

Current materials used for adipose tissue reconstruction have critical shortcomings such as suboptimal volume retention, donor-site morbidity, and poor biocompatibility. The aim of this study was to examine a controlled delivery system of dexamethasone to generate stable adipose tissue when mixed with disaggregated human fat in an athymic mouse model for 6 months. The hypothesis that the continued release of dexamethasone from polymeric microspheres would enhance both adipogenesis and angiogenesis more significantly when compared to the single-walled microsphere model, resulting in long-term adipose volume retention, was tested. Dexamethasone was encapsulated within single-walled poly(lactic-co-glycolic acid) microspheres (Dex SW MS) and compared to dexamethasone encapsulated in a poly(lactic-co-glycolic acid) core surrounded by a shell of poly-l-lactide. The double-walled polymer microsphere system in the second model was developed to create a more sustainable drug delivery process. Dexamethasone-loaded poly(lactic-co-glycolic acid) microspheres (Dex SW MS) and dexamethasone-loaded poly(lactic-co-glycolic acid)/poly-l-lactide double-walled microspheres (Dex DW MS) were prepared using single and double emulsion/solvent techniques. In vitro release kinetics were determined. Two doses of each type of microsphere were examined; 50 and 27 mg of Dex MS and Dex DW MS were mixed with 0.3 mL of human lipoaspirate. Additionally, 50 mg of empty MS and lipoaspirate-only controls were examined. Samples were analyzed grossly and histologically after 6 months in vivo. Mass and volume were measured; dexamethasone microsphere-containing samples demonstrated greater adipose tissue retention compared to the control group. Histological analysis, including hematoxylin and eosin and CD31 staining, indicated increased vascularization (p < 0.05) within the Dex MS-containing samples. Controlled delivery of adipogenic factors, such as dexamethasone via polymer microspheres, significantly affects adipose tissue retention by maintaining healthy tissue formation and vascularization. Dex DW MS provide an improved model to former Dex SW MS, resulting in notably longer release time and, consequently, larger volumes of adipose retained in vivo. The use of microspheres, specifically double-walled, as vehicles for controlled drug delivery of adipogenic factors therefore present a clinically relevant model of adipose retention that has the potential to greatly improve soft tissue repair.

Adipose derived delivery vehicle for encapsulated adipogenic factors.

Hydrogels derived from adipose tissue extracellular matrix (AdECM) have shown potential in the ability to generate new adipose tissue in vivo. To further enhance adipogenesis, a composite adipose derived delivery system (CADDS) containing single- and double-walled dexamethasone encapsulated microspheres (SW and DW Dex MS) has been developed. Previously, our laboratory has published the use of Dex MS as an additive to enhance adipogenesis and angiogenesis in adipose tissue grafts. In the current work, AdECM and CADDS are extensively characterized, in addition to conducting in vitro cell culture analysis. Study results indicate the AdECM used for the CADDS has minimal cellular and lipid content allowing for gelation of its collagen structure under physiological conditions. Adipose-derived stem cell (ASC) culture studies confirmed biocompatibility with the CADDS, and adipogenesis was increased in experimental groups containing the hydrogel scaffold. In vitro studies of AdECM hydrogel containing microspheres demonstrated a controlled release of dexamethasone from SW and DW formulations. The delivery of Dex MS via an injectable hydrogel scaffold combines two biologically responsive components to develop a minimally, invasive, off-the-shelf biomaterial for adipose tissue engineering. STATEMENT OF SIGNIFICANCE: Scientists and doctors have yet to develop an off-the-shelf product for patients with soft tissue defects. Recently, the use of adipose derived extracellular matrix (adECM) to generate new adipose tissue in vivo has shown great promise but individually, adECM still has limitations in terms of volume and consistency. The current work introduces a novel composite off-the-shelf construct comprised of an adECM-based hydrogel and dexamethasone encapsulated microspheres (Dex MS). The hydrogel construct serves not only as an injectable protein-rich scaffold but also a delivery system for the Dex MS for non-invasive application to the defect site. The methods and results presented are a progressive step forward in the field of adipose tissue engineering.

Electrospun nanofibers of poly(ε-caprolactone)/depolymerized chitosan for respiratory tissue engineering applications.

Synthetic grafts comprised of a porous scaffold in the size and shape of the natural tracheobronchial tree, and autologous stem cells have shown promise in the ability to restore the structure and function of a severely damaged airway system. For this specific application, the selected scaffold material should be biocompatible, elicit limited cytotoxicity, and exhibit sufficient mechanical properties. In this research, we developed composite nanofibers of polycaprolactone (PCL) and depolymerized chitosan using the electrospinning technique and assessed the properties of the fibers for its potential use as a scaffold for regenerating tracheal tissue. Water-soluble depolymerized chitosan solution was first prepared and mixed with polycaprolactone solution making it suitable for electrospinning. Morphology and chemical structure analysis were performed to confirm the structure and composition of the fibers. Mechanical testing of nanofibers demonstrated both elastic and ductile properties depending on the ratio of PCL to chitosan. To assess biological potential, porcine tracheobronchial epithelial (PTBE) cells were seeded on the nanofibers with composition ratios of PCL/chitosan: 100/0, 90/10, 80/20, and 70/30. Transwell inserts were modified with the nanofiber membrane and cells were seeded according to air-liquid interface culture techniques that mimics the conditions found in the human airways. Lactase dehydrogenase assay was carried out at different time points to determine cytotoxicity levels within PTBE cell cultures on nanofibers. This study shows that PCL/chitosan nanofiber has sufficient structural integrity and serves as a potential candidate for tracheobronchial tissue engineering.

Differential Aspartate Usage Identifies a Subset of Cancer Cells Particularly Dependent on OGDH.

Although aberrant metabolism in tumors has been well described, the identification of cancer subsets with particular metabolic vulnerabilities has remained challenging. Here, we conducted an siRNA screen focusing on enzymes involved in the tricarboxylic acid (TCA) cycle and uncovered a striking range of cancer cell dependencies on OGDH, the E1 subunit of the alpha-ketoglutarate dehydrogenase complex. Using an integrative metabolomics approach, we identified differential aspartate utilization, via the malate-aspartate shuttle, as a predictor of whether OGDH is required for proliferation in 3D culture assays and for the growth of xenograft tumors. These findings highlight an anaplerotic role of aspartate and, more broadly, suggest that differential nutrient utilization patterns can identify subsets of cancers with distinct metabolic dependencies for potential pharmacological intervention.